In a variety of diseases it is necessary to examine human blood for an analyte contained therein. In many cases this only requires the withdrawal of a small amount of blood in the form of a blood drop by producing a small puncture wound. A particularly important example of such a case is diabetes in which the glucose content of blood has to be examined at regular intervals. Blood may also for example be examined with regard to coagulation parameters, triglycerides, HbA1c or lactate. Blood lancet devices which consist of a lancing aid and a tailor-made replaceable lancet are usually used to produce the required puncture wounds. The housing of the lancet instrument contains a lancet holder in which one interchangeable lancet can be inserted. During the lancing operation the lancet holder is rapidly moved in a lancing direction by a lancet drive of the lancet which is also integrated into the lancing aid until the needle tip emerges from an exit opening provided at the front end of the lancing aid and produces a small puncture wound in the part of the body that is pressed against the front end. Afterwards the lancet holder containing the lancet is moved back in the opposite direction to lancing.
Small, easy-to-handle blood collection devices, so-called lancing aids that can be easily and reliably operated by the user and enable a part of the body to be lanced in an almost painless manner are now routinely used. In order to avoid infections especially in hospitals, the lancets are disposable elements intended for single use. After a lancet has been used once, the lancet is removed after the lancing operation or ejected from the device and discarded as refuse. In such a case the exposed needles in a refuse container may lead to injury during waste disposal resulting in a contamination of other persons by the used lancet. Such contamination may lead to infections and thus some countries are planning to impose a ban on blood collection systems in which the needle tip is freely accessible after use. In addition to a risk of injury during waste disposal there is also a risk that a used lancet may be accidentally re-used. This is particularly relevant for hospitals in which a lancing aid is used for several patients since such inadvertence of the nursing staff could lead to a patient being contaminated with the blood of a previous patient.
In addition to the use of blood lancet devices by medical staff, lancing aids are also used by laymen in the so-called home-monitoring field. This is particularly the case for monitoring the treatment of diabetics. Thus it has been found in the treatment of diabetics that serious damage associated with diabetes such as loss of sight can be substantially reduced when the glucose concentration in the blood of the diabetic is determined frequently and up to five times daily and the insulin injection is exactly adjusted on the basis of these measurements. Lancing aids which enable the diabetic to carry out such a blood examination are used for home-monitoring in order to carry out such frequent measurements. The resulting requirements for a blood lancet device are a simple handling when inserting new lancets and a reliable ejection of used lancets in addition to a simple handling when triggering the lancing operation and a relatively painless puncture. Lancet replacement should on the one hand be as simple as possible and, on the other hand, ensure the utmost safety with regard to unintentional injury of the user or other persons. Although in the home-monitoring field it is conceivable that a lancet, once inserted, is used several times for lancing by the same user, even in this case an accidental re-use of an ejected lancet should be prevented once the user has decided to discard the lancet. Furthermore other persons in particular should be reliably protected from the discarded lancets for example during waste disposal.
In the prior art the tip of the needle is usually surrounded by a tip cover made of plastic when the lancet is inserted which allows a safe insertion of the lancet. When the lancet is inserted, the tip cover is removed to expose the sharp tip of the needle for the lancing operation (U.S. Pat. No. 5,628,765). However, due to the exposed needle tip there is a risk of accidental injury and the tip may become damaged. The lancet is removed from the lancing aid after one or several lancing operations. This can either be carried out manually in which case there is a high risk of injury by the needle tip or by an automatic ejection mechanism.
A blood lancet device is disclosed in the patent EP 0 565 970 in which the lancet is ejected from the lancet holder by means of an ejecting rod. The user can operate the ejecting rod by pressing a corresponding button.
Furthermore an ejecting mechanism is described in the patent document U.S. Pat. No. 4,442,836 where the needle is automatically released when the lancing aid is retensioned so that the used lancet is discarded after each lancing operation. Such ejecting mechanisms require a relatively high degree of additional engineering. Moreover multiple use of an already inserted lancet system is not possible which is, however, often desired by customers especially in the home-monitoring field. Another major disadvantage of the described prior art is that the needle tip is unprotected after the lancet has been ejected resulting in a risk of injury as described above.
In order to facilitate the safe removal of a used lancet, blood collection systems are also described in the prior art which ensure the needle tip is protected after ejecting the lancet. This is regarded as an important feature especially for elderly users or those that are handicapped by poor sight and shaking hands as a result of disease.
A protection of the needle tip is achieved in the prior art by integrating the lancet in a cap of the lancing aid such that the lancet and the housing cap together form a replaceable disposable unit. Such designs are described in the documents EP 0595148 and U.S. Pat. No. 4,990,154, U.S. Pat. No. 5,454,828 and DE 10053974. When the lancet is ejected by the user, the housing cap is placed over the needle tip so that the lancet surrounded by the cap can be subsequently discarded. Even if the needle tip is protected after ejection by the described mechanism, it is nevertheless possible for a careless user to reinsert a needle that has already been ejected once and carry out a new lancing operation. Consequently the user is instructed to recognize that the needle has already been used.
Only the document EP 0 630 609 discloses a mechanism which directly prevents reinsertion and thus re-use of a lancet that has been ejected once. The described lancet device comprises a needle with a needle body which breaks when the needle is ejected from the lancing aid to prevent a reinsertion of the needle. This prevents the user from re-using a contaminated needle. However, a disadvantage of the prior art is that the needle tip is unprotected after the needle has been ejected.
The object of the invention is to provide an easy-to-use lancing aid preferably for the home-monitoring field which prevents re-use of an already ejected lancet system and also ensures a protection from injury by the needle tip after the lancet system has been ejected. It should advantageously be possible to easily reuse a needle of a lancet system that has been inserted once.
The object is achieved by a lancing aid and a lancet system according to the independent claims. Preferred embodiments are derived from the dependent claims.
The invention concerns a lancet system and a lancing aid containing the lancet system. The lancing aid has a housing for inserting a lancet system. The housing also has an opening where the needle tip can emerge from the housing and a drive mechanism for carrying out a lancing operation.
According to the invention the housing additionally has a holding element which can interact with a corresponding holding element of the lancet system as soon as the lancet system has been inserted in the lancing aid. The interaction between the holding elements enables the lancet system to be positioned in the housing at a defined site. An exact positioning of the lancet system is important especially with regard to the drive mechanism for the lancing aid since it is the only way in which the needle can be correctly coupled to the drive mechanism such that the needle can perform a lancing operation at high speed and almost without vibration. This enables a rapid and relatively painless puncture in the intended part of the body. In addition to the described holding element, the lancet system for the lancing aid comprises at least one needle with a tip which is suitable for producing an opening in the skin. The needle is connected to a needle housing and at least one protective portion of the needle housing and the needle can be moved relative to one another. In a first position the needle tip is at least partially surrounded by the protective portion of the needle housing whereas in a second position the protective portion of the needle housing and the needle tip are disposed relative to one another such that the needle tip is released from the protective portion of the needle housing. If the protective portion of the needle housing is in its first position, it thus guards against injury by the lancet tip which is particularly important after the lancet system has been ejected from the lancing aid.
The needle housing also contains a blocking mechanism which is activated by an interaction with the lancing aid. The blocking mechanism changes the needle housing in such a manner that after the lancet system has been ejected from the lancing aid, the holding element on the lancing aid can no longer interact with the holding element of the lancet system when it is reinserted. This prevents re-use of a lancet system that has been ejected once. In this connection the blocking mechanism can be automatically actuated as soon as certain operating steps have been carried out on the lancing aid. However, other embodiments are conceivable in which the user actuates the blocking mechanism by a separate operating step.
As a result of the special design of the needle housing, the lancet system according to the invention provides a protection from the needle tip such that after ejection from the lancet system the tip is surrounded by the protective portion of the needle housing to such an extent that injury by the tip is prevented. The blocking mechanism also influences the interaction of the holding elements. Within the scope of the invention the term interaction of the holding elements encompasses any conceivable embodiment that is known in the prior art for inserting and positioning a lancet or a magazine in a lancing aid. For example the holding elements can be snapped in or clamped. Suitable holding elements for this may for example be designed as locking lugs, grooves or hooks to name only a few possible embodiments. Similarly to the systems described in the prior art containing individual lancets, it is also conceivable that the lancet system is already adequately positioned and held in the lancing aid due to its coupling to the drive unit so that for example the drive unit itself can be used as a holding element for an appropriately designed lancet system.
If several holding elements are provided to position the lancet system, the blocking mechanism advantageously prevents an interaction between the holding elements of the lancet system and the lancing aid so that the lancet system cannot be held and positioned in the lancing aid. This is particularly advantageous when the lancet system and lancing aid each have several holding elements that act independently of one another.
In a preferred embodiment the interaction of the holding elements is blocked in such a manner that the lancet system is prevented from being reinserted in the lancing aid. Within the scope of the invention the term “reinsertion” encompasses a handling of the lancet system such that the lancet system is positioned at the position in the lancing aid intended for carrying out the lancing operation and is held there due to the interaction of the holding elements. For this purpose the lancet system is again used at its original position in the lancing aid thus restoring the original state of the lancet system and lancing aid which was present when the lancing aid was first used.
When operating the lancing aid, the user can advantageously immediately and unambiguously identify an already used lancet system for example due to the fact that a reinsertion of the lancet magazine into the lancing aid is blocked. Hence in contrast to the prior art the user is not required to consciously distinguish between a used lancet system and a new lancet system. Advantageously the user is spared an unnecessary reinsertion of a used lancet system which no longer functions which elderly and visually handicapped persons often find to be difficult.
However, it is also possible that the blocking mechanism only blocks the lancing operation in which case it is possible to reinsert a needle that has already been ejected. If a reinsertion of the lancet system is prevented, this usually means that the lancet system cannot couple to the drive unit.
In a preferred embodiment the blocking mechanism is essentially achieved by a change in the shape of the needle housing. This proves to be particularly advantageous when the shape of the needle housing itself forms at least a part of a holding element. It is also possible that a deformation of the needle housing spatially separates the holding elements in the lancing aid such that the blocking mechanism has an indirect effect on a holding element without directly acting on it. Hence the lancet system can no longer be positioned and held at a defined position in the lancing aid. In a preferred embodiment the deformation of the needle housing transfers the protective portion of the needle housing to a first position such that there is no risk of injury when disposing a used lancet. The protective portion of the needle housing and the blocking mechanism are then achieved as a single component of the lancet system.
In principle the holding elements can interact in a variety of ways. The blocking mechanism may have a direct or indirect effect on the holding elements. In the case of a direct effect on the holding elements, at least one holding element is advantageously changed, covered or destroyed in such a manner that interaction of the holding elements is no longer possible. Furthermore embodiments are also conceivable in which the lancet system is positioned within a lancing aid due to magnetic properties of the system. Hence a change in the magnetic properties of the needle housing could prevent a re-use of the lancet system. Appropriate magnetic elements of the needle housing or lancing aid are then the holding elements of the system.
Since the blocking mechanism advantageously only prevents a repeated insertion of the lancet system but does not prevent re-use of a needle that has already been inserted, the lancet system also satisfies requirements in the home-monitoring field where multiple use of a once inserted needle is often desired.
The lancing aid according to the invention for collecting blood has a drive unit with a plunger which moves a needle from its resting position into a lancing position. A number of drive mechanisms are known in the prior art that can be used in the field of blood collection devices (e.g. U.S. Pat. No. 5,314,442, WO 00102482, U.S. Pat. No. 3,030,959). In particular drive mechanisms are frequently used which draw their energy from a previously tensioned spring. Drive units are preferably used within the scope of the present invention which enable a guided movement of the plunger and needle for example as a result of a form-fitting coupling as described in the document DE 10053974. Guided movements of the needle for example by means of guide blocks have also been previously described in EP 0 565 970. Such drive mechanisms are preferred because the puncture is less painful. However, the system according to the invention is not limited to a particular drive mechanism, but on the contrary, can be combined with a variety of drive units.
An important aspect of the invention is a lancet system that can be detached from the drive unit containing at least one needle where the lancet system is provided as a disposable unit. In this connection the term needle encompasses a blade-shaped substantially flat lancing unit and all other conceivable embodiments thereof. In principle needles can be used for the invention that are basically well known in the prior art and can be used in a lancet system. In the prior art a needle is often combined with a base body that can couple to the lancing aid which is referred to as a lancet. Such lancets often have a base body made of plastic in which a metal needle is disposed. According to the invention it is possible to integrate such a lancet into the lancet system according to the invention. It is for example conceivable that the needle housing according to the invention contains a base body like that used for lancets in the prior art, where the inventive functionality of the system is maintained by integration of the base body. In this case the lancet system has an at least two-part design according to the described embodiment. In a preferred embodiment the needle housing is designed such that a plurality of lancets is disposed in the needle housing such that the needle housing represents a magazine containing a plurality of lancets and each base body of the lancet represents a needle body. Consequently in a preferred embodiment the protective portion of the needle housing is formed by the magazine housing. The needle and the base body can then be guided in a movable manner within the magazine. The needles within a needle housing designed according to the invention as a magazine are preferably present in separate chambers in order to prevent contamination of unused needles by used needles when reloading.
In order to carry out a lancing operation, portions of the needle body are advantageously designed like the system already described in DE 10053974 such that the individual needles of the system can be actively coupled to the drive unit of the lancing aid. Embodiments that can also be used to drive needles within a magazine of a lancing aid are described for example in the documents DE 10053974, U.S. Pat. No. 4,990,154 and U.S. Pat. No. 5,074,872. The chambers arranged next to one another in which the lancets are individually located are positioned successively relative to the drive unit in order to carry out a lancing operation in such a manner that in each case a single needle can be coupled to the plunger of the drive unit. Also in this case magazines in the form of a drum containing chambers in which the needles are located parallel to the longitudinal axis of the drum have also proven to be particularly advantageous.
The lancet system also advantageously comprises a needle housing which at least partially surrounds the needle tip by the protective portion of the housing when the needle is in its resting position. In order to carry out the lancing operation, the protective portion of the needle housing is spatially separated from the needle tip so that the protective portion of the needle housing does not hinder the lancing operation. When the lancet system is ejected from the lancing aid the needle remains in its resting position so that the ejected needle tip is protected and additionally the blocking mechanism according to the invention prevents a re-use of the lancet system. It is, however, also possible that the protective portion of the needle housing is not transferred to its first position until the lancet system is ejected so that the needle tip is only protected as a result of the ejection. In a preferred embodiment an unused needle is also in a resting position before insertion into the lancing aid to prevent injury by the needle tip and contamination when the needle is inserted as well as after ejection.
A blocking mechanism according to the invention can be actuated for example when the lancet system is ejected from or inserted into the lancing aid independently of the needle tip protection. In principle the blocking mechanism or the needle tip guards can also be activated separately or by means of individual operating steps of the lancing aid e.g. during the lancing operation. In general all possible combinations are conceivable which ensure a simultaneous or successive blocking mechanism and protection of the needle tip.
The blocking mechanism can have a variety of designs but it is advantageous that the shape of the needle housing is changed in such a manner that it is no longer possible to reinsert a lancet system once it has been ejected. For example the blocking mechanism can move at least one part of the needle housing that interacts with the lancing aid in such a manner that a change in its position blocks a reinsertion of the lancet system. This is for example the case when the blocking mechanism closes a recess in the needle housing which forms a holding element or a recess is generated in the needle housing that is essential for an interaction of the lancet system with a lancing aid. Furthermore it is also possible that the blocking mechanism comprises a predetermined breaking point which results in a breaking of the needle housing when the lancet system is ejected. It is also conceivable that the needle housing is enlarged, made smaller or bent which are only a few methods for deforming the needle housing.
According to the invention an interaction between the lancet system and lancing aid activates the blocking mechanism and sets a first position of the protective portion where the protective portion at least partially surrounds the needle tip.
An important requirement for the lancet system is that the needle tip that is used to produce a wound in an appropriate part of the body is sterile. The sterility of the needle tip has to be ensured over a long period which extends from the manufacture of the lancet system up to its use. Sterility can be achieved during the manufacture of the lancet system by for example gamma radiation which is commonly used in the prior art. In order to maintain sterility, the lancet system can be sealed in a wrapping, for example a polyethylene bag. In another embodiment the opening of the lancet system where the needle tip emerges from the protective portion of the needle housing can for example be closed by a sealing foil. These are preferably detachable sealing foils which the user removes before using the lancet system. However, it is also possible to use thin foils which are not pierced by the needle tip until the needle is used so that the user does not have to carry out additional handling steps. Such foils may already be used as an integral part of the manufacturing process for the lancet system which is usually by means of an injection moulding process.
Furthermore in the prior art an elastomer is described in the application WO 01/66010 for sterile protection which encloses the needle tip and thus protects it against contamination. This sterile protection can either be pierced during the lancing operation or be removed by the operator before use.
In another advantageous embodiment the protective portion of the needle housing can comprise a sterile protection and/or the protective portion can be essentially formed thereby. In this case the elastomer of the sterile protection serves for example as the protective portion of the needle housing by the fact that the needle tip can be moved in a guided manner relative to the elastomer. Another part of the needle housing that can be actuated independently of the sterile protection is able to change the needle housing and represents the blocking mechanism. This requires that the sterile protection can reversibly expose the needle tip and surround it again which is for example the case with an elastomer protection (WO 01/66010) in which the elastomer is firstly pierced during the lancing operation and subsequently the needle tip is retracted into the elastomer. Consequently in this example the needle tip changes its position relative to the sterile protection during the lancing operation and the needle tip is protected by the sterile protection in its resting position after the lancing operation. In principle many embodiments of a sterile protection are conceivable and hence the inventive system is not limited to any special embodiment of a sterile protection.
Further features and advantages of the invention will become apparent from the following discussion and the accompanying drawings in which: The system according to the invention is illustrated in the following on the basis of the figures and examples without being thereby limited to the individual examples.